Zhou C X, Kong L D, Ye W C, Cheng C H, Tan R X
Planta Med. 2001 Mar;67(2):158-61. doi: 10.1055/s-2001-11500.
The bioassay guided refractionation of the methanol extract of roots and rhizomes of Veratrum taliense (Liliaceae) yielded five stilbenoids: veraphenol, resveratrol, piceid, isorhapontin, and mulberroside E, all inhibiting xanthine oxidase (XO, EC 1.2.3.2.) in vitro in a dose-dependent manner with IC50 values of 11.0, 96.7, 66.1, 70.0, and 78.4 microM, respectively. Veraphenol and mulberroside E were found to be mixed XO inhibitors with the Ki and Ki data of the former being 32.8 and 239.3 microM, and those of latter 32.5 and 13.8 microM, respectively. However, the inhibition on the enzyme by resveratrol, isorhapontin, and piceid was shown to be competitive with their Ki values of 9.7, 19.1, and 14.3 microM, respectively. Among the five stilbenoids, veraphenol and resveratrol were also revealed to inhibit competitively monoamine oxidase A (MAO, EC 1.4.3.4) with IC50 values at 38.0 and 26.6 microM, and Ki data 36.4 and 47.3 microM, respectively. However, none of the stilbenoids was inhibitory on MAO B in our assay. The structure-activity relationship examination showed that glycosylation of the stilbenoids could reduce the inhibition on XO and diminish the activity against MAO A, indicating that the free phenolic hydroxy group of the compounds was most likely essential for these bioactivities.
对藜芦（百合科）根及根茎的甲醇提取物进行生物测定导向的重分馏，得到了五种芪类化合物：藜芦酚、白藜芦醇、云杉新苷、异丹叶大黄素和桑辛素E，它们在体外均能以剂量依赖性方式抑制黄嘌呤氧化酶（XO，EC 1.2.3.2.），IC50值分别为11.0、96.7、66.1、70.0和78.4微摩尔。发现藜芦酚和桑辛素E为混合型XO抑制剂，前者的Ki和Ki'数据分别为32.8和239.3微摩尔，后者分别为32.5和13.8微摩尔。然而，白藜芦醇、异丹叶大黄素和云杉新苷对该酶的抑制作用表现为竞争性，其Ki值分别为9.7、19.1和14.3微摩尔。在这五种芪类化合物中，藜芦酚和白藜芦醇还显示出对单胺氧化酶A（MAO，EC 1.4.3.4）有竞争性抑制作用，IC50值分别为38.0和26.6微摩尔，Ki数据分别为36.4和47.3微摩尔。然而，在我们的测定中，没有一种芪类化合物对MAO B有抑制作用。构效关系研究表明，芪类化合物的糖基化可降低对XO的抑制作用，并减弱对MAO A的活性，这表明化合物的游离酚羟基很可能是这些生物活性所必需的。
